The invention relates to a lockable safety shield assembly for a prefillable syringe, and more particularly, to a lockable safety shield assembly for a prefillable syringe which is easily attached to a prefillable syringe and which can be subsequently activated by an end-user to form a locking mechanism for the shield.
As is known in the art, syringes are medical delivery devices utilizable to administer a medicament to a patient. Syringes are normally provided in prefillable form, wherein a set dosage of medicament can be filled into the syringe by a pharmaceutical manufacturer for distribution to the end user, or they are empty and intended to be filled by the end user from a vial or other source of medicament at the time administration of the medicament is desired.
Syringes typically include a barrel portion adapted to retain the medicament. The distal end of the barrel is normally configured to mate with a conventional piercing element, such as a pointed needle cannula made of steel or like material or a blunt ended cannula formed of plastic, to deliver the medicament contained in the barrel. A plunger rod is inserted through the open distal end of the syringe barrel and, through its engagement with an elastomeric or rubber-like stopper element fitted in a fluid-tight manner within the interior of the barrel, a user can apply manual force to the plunger to deliver the medicament through the piercing element.
More typically the case with pointed needle cannulae, accidental needle sticks that occur after the needle cannula has been used generally pose a greater health risk. To avoid such accidents, many prior art hypodermic syringes include a rigid cylindrical safety shield telescoped over the syringe barrel. The prior art safety shield can be slid from a proximal position where the needle cannula is exposed for use, to a distal position where the safety shield protectively surrounds the needle cannula.
Most prior art hypodermic syringes with cylindrical safety shields telescoped over the syringe barrel include structure for locking the safety shield in its distal position. Examples of such structures are found, for instance, in U.S. Pat. Nos. 5,342,309 and 5,385,555 to Hausser and U.S. Pat. No. 5,304,149 to Morigi.
While generally suitable for the tasks employed, further improvements are still being sought. For instance, where the syringe is prefillable by a pharmaceutical manufacturer, it would be beneficial to incorporate improvements into the locking structure employed with the safety shields to better facilitate a pharmaceutical manufacturer""s processing of the various components associated with the syringe barrel and safety shield. These improvements should also facilitate the end user""s normal use of the prefillable syringe and easy activation of the safety shield once safe disposal of the syringe is desired. Moreover, most of the prior art approaches focus their efforts on employing a plastic collar element on some distal portion of the syringe barrel, with the shield locking onto the collar. While a valid approach, because many of the prefilled syringes currently in use are made of glass, it can be difficult to assemble the plastic collar element onto the syringe barrel. Accordingly, it would be useful to design a structure whereby the collar were incorporated as part of the shield structure itself.
A lockable safety shield assembly for prefillable syringes is provided. The lockable safety shield is designed to facilitate a pharmaceutical manufacturer""s assembly of the various components associated with the lockable safety shield onto the syringe in conjunction with how the syringes are normally processed by the pharmaceutical manufacturer. The locking structure associated with the safety shield of the present invention may be designed such that it will not interfere with easy assembly by the pharmaceutical manufacturer, but which can be easily activated by an end user to facilitate safe covering of the distal end of a piercing element once the prefillable syringe has been used.
The assembly includes a tube mounted about the outside surface of the syringe barrel. The tube can be locked, for instance, to the flange provided about the proximal end of the syringe barrel. The tube features a collar positioned adjacent the distal end of the syringe barrel. The collar can be configured as a flat, disk-like structure formed in an annular manner about the outside of the tube.
A safety shield is coaxially mounted over the tube. The safety shield is axially movable between a retracted position, wherein the distal tip of a piercing element affixable to the barrel is exposed, and an extended position, wherein the distal tip of the piercing element will be covered. The safety shield includes a proximal end, a distal end, and a circumferential sidewall therebetween. The circumferential sidewall has an outside surface and an inside surface. Particularly, the shield is provided with user-activatable locking structure to secure the shield in its extended position respective of the syringe.
In one configuration, the locking structure includes at least one deflectable arm incorporated as part of the structure of the sidewall. The deflectable arm includes a distal end mounted with the circumferential sidewall, and a proximal end which is deflectable towards the interior of the shield. At least one stop member is mounted to the interior surface of the shield and spaced a distance from the proximal end of the deflectable arm to define a gap between the stop member and the proximal end of the deflectable arm. The deflectable arm has a free position, wherein the outside surface of the arm is substantially co-planar with the outside surface of the circumferential sidewall, and a locking position, wherein the deflectable arm is urged towards the interior of the shield so that the proximal end of the deflectable arm is positioned towards the interior of the shield.
Means are provided on the shield to activate the locking structure. In one configuration, a circumferential ring is axially slidable about the outside surface of the shield between a first position, wherein the ring is spaced away from the deflectable arm, and a second position, wherein the ring is positioned against the at least one deflectable arm to secure the arm in the locking position. The ring may be secured to the distal end of the shield by a user-severable connection. The user-severable connection may entail, for instance, one or more frangible sections of material provided between the ring and the distal end of the shield. A pair of spaced abutments may be provided on the outside surface of the deflectable arm to retain the ring in its second position.
In practice, the safety shield assembly is typically preassembled by the syringe manufacturer and supplied to the pharmaceutical manufacturer in a sterile state, ready for attachment to the prefillable syringe once it has been filled with a desired drug.
After the syringe has been filled with the drug and otherwise subjected to various processing operations, such as various particulate inspection operations, labeling operations, plunger rod assembly operations, or the like, the safety shield assembly can be easily fitted to the syringe. The tube is fitted about the syringe barrel and clipped onto the flange of the syringe barrel. In the preassembled state, the shield located respective of the tube such that the shield will be placed in a retracted position vis-a-vis the piercing element. Various structures associated with the tube may be provided with sloped surfaces to ensure smooth placement of the safety shield assembly over the syringe flange.
Subsequent to placing the shield assembly onto the syringe barrel, the locking structure must be activated. The locking structure is activated by detaching the ring from its user-severable connection, and sliding the ring proximally so that it is engaged between the abutments provided on the deflectable arm. If desired, the device may be shipped by a pharmaceutical manufacturer to an end user with the ring connected to the shield by its user-severable connection, so that the end-user himself activates the locking structure. Alternately and preferably, the pharmaceutical manufacturer activates the locking structure as part of the assembly process, such that the filled syringe with safety shield assembly is shipped to an end-user with the locking structure already activated.
After the syringe has been used to administer an injection, the shield is slid distally over the tube. The collar will be captured between the proximal end of the deflectable arm and the stop member in order to lock the shield in its extended position. In a preferred embodiment, the deflectable arm, the collar, and the stop member may be configured to provide audible as well as tactile indication to the end user that the shield has been securely locked with the collar.
In a preferred embodiment, at least two deflectable arms are provided. The two deflectable arms are located on diametrically opposite sides of the shield. Correspondingly, two stop members are provided to interact with the two deflectable arms. When viewed along the central axis of the shield, the stop members can be circumferentially aligned with a respective proximal end of the deflectable arms, or they can be circumferentially offset from a respective proximal end.